RECENT SUBMISSION

• Publication

  Optimization of graphene infused natural rubber sensing film and polydimethylsiloxane for flexible pressure sensor

  ( 2023-12)

  Vishnukumar Rajandran

  ;

  Ab Rahman Marlinda

  ;

  Azim Danial Azam

  ;

  Md. Shalauddin

  ;

  A. A Saifizul

  ;

  Syed Muhammad Hafiz

  ;

  Shafarina Azlinda

  A flexible and stretchable pressure sensor offers significant benefits in human-computer interaction, healthcare, and tactile sensing in robots. We present a novel study optimising Polydimethylsiloxane (PDMS) and graphene-infused unvulcanised natural rubber sensing film to increase sensor sensitivity and dielectric permittivity. By optimising the PDMS thickness uniformity, NR-G film’s impedance and capacitance-pressure loading response, it is possible to enhance the pressure sensor's sensitivity across a wide pressure range, covering human finger motion. With our synthesized homogenous 5wt% of NRG composite, a capacitance value of 193pF was achieved when applying pressure of 150 kPa at a frequency of 0.5 Hz. Excellent sensitivity and dielectric permittivity of 0.020 kPa-1 and 109.1, respectively, which is ~ 6.5 folds higher than pure NR. PDMS thickness of 300μm with ±3% uniformity was achieved using 90s spin time and 200rpm spin speed. This optimisation of sensing material and substrate is important in developing wearable sensors having applications in soft robotics, health monitoring electronics, and soft human-machine interfaces.
• Publication

  Optimization of gold nanoparticles electrodeposition duration on screen printed electrode to enhance electrochemiluminescence of nitrogen-doped carbon dots

  ( 2023-12)

  Nurul Izzati Akmal Mohd Azman

  ;

  Nur Syakimah Ismail

  ;

  Nur Hamidah Abdul Halim

  ;

  Nurjuliana Juhari

  ;

  Norhayati Sabani

  ;

  Toibah Abd Rahim

  ;

  Siti Aisyah Shamsudin

  ;

  Eiichi Tamiya

  In this work, the electrodeposition method was utilized to form gold nanoparticles on a carbon screen-printed electrode (SPE) using chronoamperometry at -0.4 V with various durations from 50 to 200 seconds. Scanning Electron Microscopy (SEM) images have proven that the electrodeposition method is capable of uniformly forming AuNPs on SPE (AuNPs- SPE). Apart from that, electrodeposition durations have increased the size of AuNPs by up to 66% based on average size measurements using ImageJ software. It can be observed that long electrodeposition durations permit the agglomeration of AuNPs on the electrode surface. The effect of electrodeposition duration on electrocatalytic performance in potassium ferricyanide and electrochemiluminescence (ECL) intensity of nitrogen-doped carbon dots (NCDs) was evaluated. Cyclic voltammetry (CV) of ferricyanide demonstrates that as the electrodeposition duration increases, AuNPs-SPE shows better electrochemical performance than bare SPE. ECL of NCDs displays that 100 s electrodeposition durations give the highest ECL intensity of 184% compared to bare SPE and have been chosen as the optimum parameter. The ECL mechanisms of bare SPE and AuNPs-SPE reveal that AuNPs- SPE has greater electrochemical and ECL performance than bare SPE, as evidenced by the CV of AuNPs-SPE having a faster reduction current, which rises to 87.2% ECL intensity and 510 mV faster ECL occurrence. These phenomena confirmed that the electrodeposition of AuNPs has improved the conductivity of SPE.
• Publication

  Numerical simulation of lead-free tin and germanium based all perovskite tandem solar cell

  ( 2023-12)

  Rae-Ann Lim Jia En

  ;

  Ayu Wazira Azhari

  ;

  Dewi Suriyani Che Halin

  ;

  Suhaila Sepeai

  ;

  Norasikin Ahmad Ludin

  The ability to customize the materials bandgaps makes perovskite solar cells a promising candidate for hybrid-tandem applications. This allows them to effectively utilize parts of the solar spectrum that silicon-based solar cells cannot efficiently capture, resulting in higher absorption coefficients. However, there is a lack of research on lead-free all-perovskite tandem solar cells, and secondary data on materials is limited. One of the main challenges in previous studies is the high cost and solid structure of traditional silicon-based solar cells, which require significant storage space. Additionally, lead-based perovskite solar cells pose environmental concerns due to their water solubility and potential harmful effects upon consumption. To address these issues, thin-film perovskite solar cells with liquid solvents are employed in the solar cell design. Lead is replaced with germanium and tin-based perovskites, which exhibit comparable photovoltaic performance to silicon. In the present work, the OghmaNano simulation tool was utilized to conduct numerical simulation of the perovskite design. The perovskite solar cell layers were structured as follows: FTO/ZnO/MAGeI3/Spiro-OMeTAD/FAMASnGeI3/Cu2O/Au. The variables considered included optimum layer thicknesses and bandgaps, as well as the most suitable materials for the ETL and HTL, aiming to obtain the highest efficiency. Based on the simulation results, the proposed perovskite structure shows remarkable photovoltaic parameters. The Voc was measured at 0.84 V Jsc of 16.1 mA/cm2, FF of 0.825, and PCE that reached 11.12%. This project contributes to future research on materials for the ETL and HTL of lead-free, tin and germanium based APTSCs.
• Publication

  Investigation on phase evaluation of ilmenite ore by carbothermal reduction and carboiodination reaction

  ( 2023-12)

  A. A. Adel

  ;

  Nur Farhana Diyana Mohd Yunos

  ;

  Muhammad Asri Idris

  ;

  L. I. G. Togang

  This article presented the thermochemical calculation and experimental investigation on the phase evaluation of ilmenite ore (FeTiO3) via carbothermal reduction and carboiodination reaction for titanium production using graphite as a reducing agent. The carbothermal reduction and carboiodination reactions were performed in two different furnaces. The carbothermal reduction was evaluated at a temperature of 1550°C with inert argon gas utilizing a horizontal tube furnace. The carboiodination reactions were evaluated in temperatures ranging from 900°C, 950°C, and 1000°C using a vertical tube furnace with mixed iodine gas with argon gas. XRF and XRD were used for analyzing the chemical compositions and the phase evolutions of raw ilmenite ore and the reduced samples, respectively. The findings showed that the Perak ilmenite ore predominantly has a greater concentration of TiO2 (71.27wt%), Fe2O3 (18.85wt%), and some other oxides like aluminum oxide and quartz. In addition, XRD revealed that the ilmenite phase was converted into rutile (TiO2) titanium oxide (Ti3O5, Ti2O3), titanium carbide (TiC), and iron (Fe) phases, after the carbothermal reduction process. However, after the carboiodination reaction, the ilmenite and rutile phases remained at temperatures 900°C, 950°C, and 1000°C. The HSC Chemistry software was used in the determination of the thermochemical calculation and the possible reactions during the reaction which play an important role in shortening the reduction process. The results revealed the carboiodination process is a promising process that can reduce energy consumption and shorten the titanium production processes, and it needs more studies.
• Publication

  Synthesis and characterization of SrTiO₃ doped with Bi(CH₃COO)₃

  ( 2023-12)

  Mahfuddin Zuhri

  ;

  Hilal Fauzi Ramadhan

  ;

  Irzaman

  Synthesis of Strontium Titanate (SrTiO₃ ) doped with Bismuth Acetatem (Bi(CH₃COO)₃) has been successfully carried out with varying concentrations of 0%; 0.5%; 1%; and 1.5% impurity in weight percent. The concentrated solution was dripped onto a P- type silicon substrate (1 0 0) using the Chemical Solution Deposition (CSD) method and spin coating technique. Annealing process was carried out with a temperature increase of 1.67oC/minute and held at 850oC for 8 hours and then cooled to room temperature for 12 hours. The film thickness was determined by the volumetric method, resulting in values of 3.9 μm, 4.3 μm, 4.7 μm and 5.1 μm. The analysis of optical properties with the Kubelka-Munk function for the direct transition results a band gap of 3.46 - 3.56 eV. Analysis of the XRD results was carried out using the Cramer-Cohen method and obtained lattice parameters (a=b=c) of Strontium Titanate (SrTiO3) doped with Bismuth Acetate (Bi(CH₃COO)₃) with various concentrations of 0%; 0.5%; 1%; and 1.5% are 3.835 Å, 3.837 Å, 3.909 Å, 3.913 Å respectively with a cubic crystal structure. This is because the ionic radius of bismuth (1.32 Å) is larger than that of strontium (1.17 Å), so bismuth will replace strontium in thin films. This replacement causes the lattice parameter values to increase, and effects the XRD spectral curve at the preferred peak (1 1 0) shift to the left. This shows that the doping bismuth has entered the strontium host.